Vote up?

I’d like to “second” the urge of caution when developing with libraries such as IE7, not so much because of the IE6/noJS incompatibility, but because of what the crutch does to you.

For the majority of sites, the most crucial of elements (navigation, calls to action, etc.) should not require extra logic (Javascript) to function. Enhancement, of course, is perfectly acceptable.

There was an article in recent news of how Yahoo! Sports had a syntax error in the minified Javascript served to users. Many sites would simply stop functioning or lose significant features. Yahoo! Sports continued working just fine, thanks to what many call Progressive Enhancement.

As for using IE7 for fixing box-model issues with IE6, many CSS frameworks that support grid-based layouts (BlueprintCSS) take care of this already.